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Oxygen non-stoichiometry, electrical...

Yoo, Jiho.

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Oxygen non-stoichiometry, electrical conductivity, and oxygen transport property in mixed conducting perovskite oxides.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Oxygen non-stoichiometry, electrical conductivity, and oxygen transport property in mixed conducting perovskite oxides./
Author:	Yoo, Jiho.
Description:	184 p.
Notes:	Source: Dissertation Abstracts International, Volume: 63-12, Section: B, page: 5841.
Contained By:	Dissertation Abstracts International63-12B.
Subject:	Chemistry, Inorganic. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3076158
ISBN:	0493962778

Oxygen non-stoichiometry, electrical conductivity, and oxygen transport property in mixed conducting perovskite oxides.
Yoo, Jiho.

Oxygen non-stoichiometry, electrical conductivity, and oxygen transport property in mixed conducting perovskite oxides. - 184 p.

Source: Dissertation Abstracts International, Volume: 63-12, Section: B, page: 5841.

Thesis (Ph.D.)--University of Houston, 2002.

The experimental results from solid-state coulometric titrations and electrical conductivity relaxation measurements on SrFeO3-delta are described. In coulometric titration experiments, two-phase behavior at T ≤ 850°C was observed as hysteresis in the oxygen non-stoichiometry (delta) isotherms. The p to n transition in the electrical conductivity (sigmatot) isotherms is found to occur at the composition, SrFeO2.505 at 950°C and SrFeO2.508 at 900°C, respectively. Values of vacancy diffusion coefficient ( Dnu) for SrFeO3-delta is ≈1.5&sim;5 times smaller than for the La1-xSrxFeO3-delta series probably due to stronger defect interactions. Values of oxygen ion diffusion coefficient ( DO2- ) and surface exchange coefficient (kex) for SrFeO3-delta are much greater than for the La 1-xSrxFeO3-delta series, because of its higher delta-values.

ISBN: 0493962778Subjects--Topical Terms:

517253
Chemistry, Inorganic.

Oxygen non-stoichiometry, electrical conductivity, and oxygen transport property in mixed conducting perovskite oxides.
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020 $a 0493962778
035 $a (UnM)AAI3076158
035 $a AAI3076158
040 $a UnM $c UnM
100 1 $a Yoo, Jiho. $3 1952642
245 1 0 $a Oxygen non-stoichiometry, electrical conductivity, and oxygen transport property in mixed conducting perovskite oxides.
300 $a 184 p.
500 $a Source: Dissertation Abstracts International, Volume: 63-12, Section: B, page: 5841.
500 $a Adviser: Allan J. Jacobson.
502 $a Thesis (Ph.D.)--University of Houston, 2002.
520 $a The experimental results from solid-state coulometric titrations and electrical conductivity relaxation measurements on SrFeO3-delta are described. In coulometric titration experiments, two-phase behavior at T ≤ 850°C was observed as hysteresis in the oxygen non-stoichiometry (delta) isotherms. The p to n transition in the electrical conductivity (sigmatot) isotherms is found to occur at the composition, SrFeO2.505 at 950°C and SrFeO2.508 at 900°C, respectively. Values of vacancy diffusion coefficient ( Dnu) for SrFeO3-delta is ≈1.5&sim;5 times smaller than for the La1-xSrxFeO3-delta series probably due to stronger defect interactions. Values of oxygen ion diffusion coefficient ( DO2- ) and surface exchange coefficient (kex) for SrFeO3-delta are much greater than for the La 1-xSrxFeO3-delta series, because of its higher delta-values.
520 $a Electrical conductivity data for La0.2Sr0.8Cr 0.2Fe0.8O3-delta were obtained at 752 ≤ T ≤ 1055°C and at 10-18 ≤ pO2 ≤ 0.5 atm. The slope of a plot of log sigma vs. log pO2 is &sim;1/5 in the p-type region. At T ≤ 940°C, a plateau in the conductivity isotherms indicates the presence of a two-phase region most probably corresponding to a mixture of perovskite and an oxygen vacancy ordered phases. Electrical conductivity relaxation measurements were performed to investigate the kinetics of oxygen transport at 800 ≤ T ≤ 1000°C and at 0.01 ≤ pO2 ≤ 1 atm, having values of Dchem = 1.62 x 10 -4 &sim; 3.10 x 10-4 cm2/s at 950°C with an activation energy (Ea) of 84 +/- 14 kJ/mol. The oxygen ion diffusion coefficient ( DO2- ) and surface exchange coefficient (kex) of La0.2Sr0.8Cr0.2Fe0.8O 3-delta are relatively high because of high oxygen vacancy concentration.
520 $a The experimental results of electrical conductivity measurements and solid-state coulometric titrations on La0.5Sr0.5Ga 0.2Fe0.8O3-delta are reported. The effect of oxygen partial pressure (pO2) on electrical conductivities of La0.5Sr0.5Ga0.2Fe0.8O3-delta was investigated at 750 ≤ T ≤ 1050°C and at 10-17 ≤ pO2 ≤ 0.5 atm. At 10-5 ≤ pO2 ≤ 0.1 atm the log sigmatot is almost proportional to log (pO2) with a slope of ≈¼ slope. At T ≤ 850°C, a plateau and a rapid increase in the conductivity isotherms indicate a presence of a two-phase region. In a plot of log pO 2 vs. oxygen non-stoichiometry discontinuity appears at T ≤ 900°C and at the pO2 region where the two-phase region was observed from the conductivity results. The p to n transition in the conductivity isotherms occurs at the composition, La0.5Sr0.5Ga0.2Fe 0.8O2.749&sim;2.750 at 850°C and La0.5Sr 0.5Ga0.2Fe0.8O2.748&sim;2.749 at 900°C, respectively.
520 $a The oxygen transport kinetics in La0.5Sr0.5FeO 3-delta were investigated using the electrical conductivity relaxation technique at 788 ≤ T ≤ 943°C and at 0.03 ≤ pO 2 ≤ 1 atm. (Abstract shortened by UMI.)
590 $a School code: 0087.
650 4 $a Chemistry, Inorganic. $3 517253
650 4 $a Engineering, Materials Science. $3 1017759
690 $a 0488
690 $a 0794
710 2 0 $a University of Houston. $3 1019266
773 0 $t Dissertation Abstracts International $g 63-12B.
790 1 0 $a Jacobson, Allan J., $e advisor
790 $a 0087
791 $a Ph.D.
792 $a 2002
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3076158